1. Field of the Invention
This invention relates to an apparatus for needling a nonwoven web, comprising a slider-crank mechanism, which is connected to a rocker and serves to actuate at least one needle board, which is secured to the rocker, and web-guiding means comprising a web support, which is opposite to the needle board, and a stripper, which extends between the web support and the needle board.
2. Description of the Prior Art
Needle boards are actuated by slider-crank mechanisms either by means of push rods, which are slidably mounted in guides, or by means of rockers, which carry the needle boards and to which the slider-crank mechanisms are pivoted (Austrian Patent Specification 249,392). The use of a rocker for guiding the needle boards affords the advantage that the structure is simpler because the need for providing push rods and associated guides between the connecting rods of the slider-crank mechanisms and the needle beam, which carries the needle boards, is eliminated. Besides, the needling operation performed by a needle board which is guided by a rocker will differ from the needling operation performed by a needle board which is reciprocated along a straight line because the conditions for the penetration of the needles are different and this can be utilized for achieving different needling effects. For instance, the mean inclination of the paths along which the needles of the needle board penetrate the nonwoven web relative to the direction of travel of the web can be adjusted, either in that the axis of rotation of the rocker is displaced in the direction in which the needle board is reciprocated or in that the web-guiding means are pivotally moved about a pivotal axis which is disposed adjacent to the middle of the web-guiding means and parallel to the pivotal axis of the rocker. Because the needle boards are usually so arranged that the needles are inclined relative to the mean penetration path, the holes in which the needles pass through the stripper and through the web support must consist of slots so that the needle density is restricted and this may adversely affect the result of the needling operation.